An image forming apparatus is capable of carrying out an image forming process with an erasable coloring material and a non-erasable coloring material. Another image forming apparatus is capable of carrying out an image erasing process of a fixed image formed with an erasable coloring material, using a fixing unit used for the image forming process. Such an image forming apparatus may be a printer, a multi function peripheral (MFP), and the like. A fixing temperature of an unfixed image may be different depending on the coloring material of the unfixed image, and an erasing temperature of a fixed image may also be different depending on the erasable coloring material of the fixed image. For example, when a fixing temperature of an unfixed image formed with an erasable coloring material is different from a fixing temperature of an unfixed image formed with a non-erasable coloring material, the image forming apparatus needs to change the fixing temperature according to the fixing target. However, it may take a significant amount of time for the image forming apparatus to increase and decrease the fixing or the erasing temperature when the target is switched. This process time may decrease usability of the image forming apparatus.